/**
 * 二叉树 类
 */
public class TreeNode {
    int val;  // 节点值
    TreeNode left;  // 左子树
    TreeNode right;  // 右子树

    TreeNode() {

    }

    TreeNode(int val) {
        this.val = val;
    }

    TreeNode(int val, TreeNode left, TreeNode right) {
        this.val = val;
        this.left = left;
        this.right = right;
    }
}
